1. Field of the Invention.
This invention relates generally to disposable pumping chamber cassettes which are used with fluid pumps. The cassette of the present invention is useful for pumps wherein the fluid is to be selectively pumped from either or both of two fluid sources to a patient. This invention is particularly, though not exclusively, useful in conjunction with a pump used for the infusion of I.V. fluids to a patient.
2. Background of the Invention.
The present invention is directed to a pumping chamber for use with a volumetric infusion pump that is particularly adaptable for administering fluids to a patient. When a person is hospitalized, it is often desirable to administer one or more fluids to the patient for either therapeutic or maintenance purposes. Further, it is not uncommon that the concurrent infusion of more than one solution is required.
A common method for introducing medical solutions directly into the patient's bloodstream is by intravenous (I.V.) administration. Under appropriate circumstances, this method affords several advantages. For example, the necessity of giving repeated injections to the patient, and the traumatic response most patients have towards repeated injections, can be eliminated by the use of a standard intravenous (I.V.) procedure. Additionally, precise quantities of the selected solution can be properly administered over protracted periods of time.
An I.V. administration procedure typically requires suspending a container of fluid at an elevated position with respect to the patient. The container is then placed in fluid communication with the patient through a series of tubes and connections which lead to a needle that has been placed into one of the patient's veins. Obviously, the rate of fluid flow and the volume of fluid infused through such a system must be controlled. For this purpose, pumps or controllers can be used in such procedures. Specifically, pumps can be used in I.V. systems for the administration of fluids to a patient when there is a need to provide a mechanical pressure on the fluid being infused.
Volumetric pumps, capable of both fluid volume and flow rate control, typically incorporate a pumping chamber with a valving device which allows the pumping chamber to alternately fill and discharge in accordance with the predetermined rate of fluid flow to the patient. Several examples of these types of I.V. pumps and associated disposal pump chamber cassettes are available. Specifically, U.S. Pat. No. 3,985,133 to Jenkins et al., U.S. Pat. No. 4,423,741 to Levy, and U.S. Pat. No. 4,450,079 to Farr disclose pumps or pump chamber cassettes for an I.V. pumping device.
Further, several valving mechanisms have been suggested for use with pumping chambers. For example, U.S. Pat. No. 3,269,412 to Badke and U.S. Pat. No. 4,423,741 to Levy disclose reciprocating piston valves having various fluid paths defined therein which are oriented with fluid inlets and outlets to a single fluid path through a common chamber. These devices, however, are not able to channel multi-inlet sources to a common pumping chamber and eventually to an outlet. As an added feature, U.S. Pat. No. 4,605,396 to Tseo discloses a pump cassette having the ability to establish a free-flow condition from the inlet to the outlet of the cassette. Again, as with the above-identified references, Tseo does not teach or suggest a cassette with the ability to have two inlet sources feeding a chamber, which subsequently pumps fluid into a patient.
To improve the flexibility of a pumping mechanism in an I.V. infusion system, there is a recognized need for a combination between pumping chamber and valve which provides for the option of using alternate fluid sources either separately or in conjunction with each other. Further, there is a need for such an option without disconnecting the fluid line or interrupting the infusion. With this in mind, it can be appreciated that there is a need for a cassette which can switch to a second fluid source, after a preprogrammed infusion from a first fluid source, and allow fluid from the second source to be pumped through the system. There is also a need for a pump cassette having a chamber for accurately mixing fluid solutions from separate sources at desired concentrations.
The present invention recognizes that the aforementioned needs can be satisfied by a cassette which employs a valve having channels and/or grooves which create passageways by rotational or longitudinal displacement of the valve. Further, the present invention recognizes that this valve in cooperation with a pump cassette will be useful to administer a predetermined quantity of fluids from at least two fluid sources to the patient.
Accordingly, it is an object of the present invention to provide a means for drawing a first medical solution into a chamber, while also having the ability to draw a second medical solution into the same chamber. It is another object of the present invention to provide a pump cassette having means for engaging or disengaging a second I.V. fluid line without interrupting the administration of fluids to the patient from an established I.V. line. Additionally, it is an object of the present invention to provide an inexpensive, easily manufactured and simple to operate device that improves the flexibility of an I.V. administration system.